The present invention relates generally to integrated circuits, and, more particularly, to a configurable driver circuit that can operate in multiple signaling modes.
Driver circuits, or simply “drivers,” transmit data in the form of electrical signals over various communication channels such as transmission lines, cables, printed circuit board traces, and integrated circuit traces. For example, drivers are used at the edges of integrated circuit to transmit signals generated on-chip to off-chip circuitry.
Drivers typically are designed to operate in a particular signaling mode, such as a single-ended voltage signaling mode, single-ended current signaling mode, or differential signaling mode. In the single-ended voltage and single-ended current signaling modes, the driver transmits the data as a varying voltage signal or a varying current signal over a single conductor, respectively. In differential signaling mode, the driver transmits the data as complementary signals over a pair of conductors.
Each driver has a specific design that enables it to operate in one of the signaling modes. Hence, to implement multiple signaling modes on the IC, output terminals of the drivers that operate in one of the aforementioned modes are multiplexed on a single input/output (IO) pad of the IC. However, multiplexing multiple drivers on the IO pad increases the load capacitance at the IO pad, which reduces the speed of the driver. Further, implementing multiple drivers consumes a significant amount of area. One solution for accommodating multiple signaling modes on an IC is to integrate the drivers on dedicated IO pads. However, having several such IO pads increases area and design complexity. Another solution is to have a driver that may be configured to operate in either single-ended or differential signaling mode. However, multiplexing different IO protocols comes with integration challenges and operational compatibility issues.
Therefore, it would be advantageous to have a configurable driver circuit that is not overly complex and does not consume excessive area.